The Medical Breast Cancer Section is responsible for the development of a clinical and laboratory program directed at breast cancer. Clinical trials in metastatic disease comparing chemotherapeutic, hormonal and chemohormonal regimens are underway. Biochemical and hormonal marker studies are undertaken and coordinated by the Medical Breast Cancer Section. These studies consist of a major chemotherapy trial aimed at synchronizing human breast cancer cells with hormonal agents for more successful cell cycle phase specific chemotherapy; a hormonal therapy trial aimed at prospectively evaluating the usefulness of steroid receptors for estrogens, androgens and progestins in human breast cancer; an advanced disease hormonal therapy trial comparing tamoxifen to tamoxifen plus an androgen, several phase II trials including a trial of PALA and 5FU in combination and 13 Cis Retinoic acid. In addition there is an endocrine and chemotherapy program for male breast cancer. Surgery, Radiation and Medicine Branches are underway comparing excisional biopsy plus definitive radiotherapy to simple mastectomy in clinical Stage I and II breast cancer. All patients have axillary dissections; A-C chemotherapy is given to all N plus patients. Finally, a prospective phychological study aimed at discovering whether or not patients' emotional response to their disease influences outcome is underway.